Irritation caused by hollow cough and a smile (7)
I believe the answer is:
chagrin
'irritation' is the definition.
'hollow cough and a smile' is the wordplay.
'hollow' means to remove the middle letters.
'and' is a charade indicator (letters next to each other).
'smile' becomes 'grin' (grinning is a kind of smiling).
'cough' with its middle removed is 'ch'.
'ch'+'a'+'grin'='CHAGRIN'
'caused by' acts as a link.
(Other definitions for chagrin that I've seen before include "Feeling of annoyance and embarrassment" , "Arching with annoyance and embarrassment" , "Arching with annoyed disappointment" , "Acute annoyance or disappointment" , "Feeling of annoyance and disappointment" .)